Query elements inside <content> of a custom element - dart

Question

I have two custom elements. The one of them is nested to another one. Something like this:
<polymer-element name="my-element">
<template>
<div>
Bla, Bla, Bla!
</div>
</template>
<script type="application/dart" src="my_element.dart"></script>
</polymer-element>
<polymer-element name="my-decorator">
<template>
<div>
<div>Decorator</div>
<content>
<!-- my-element will be here-->
</content>
</div>
</template>
<script type="application/dart" src="my_decorator.dart"></script>
</polymer-element>
using both custom elements in index.html:
<my-decorator>
<my-element></my-element>
</my-decorator>
How can I query the instance of the second element from the code behind of the first one?
#CustomTag('my-decorator')
class MyDecorator extends PolymerElement {
bool get applyAuthorStyles => true;
MyDecorator.created() : super.created() {
// TODO:
// get my-element instance here!
// ..
}
}

Answer 1

#override
void attached() {
// attached is an example the code an be placed somewhere else
// but some places are executed before the childs are added
super.attached();
var nodes = (shadowRoot.querySelector('content') as ContentElement).getDistributedNodes();
var myElement = nodes.firstWhere((e) => e is MyDecorator); // not sure about this `e is MyDecorator`
// you have to choose some way to identify the node in the result
// I currently have no example where I can try it myself
}
if the tag has an id attribute like id='c1' then this works too
var nodes = ($['c1'] as ContentElement).getDistributedNodes();